This invention relates to drip coffeemakers and in particular to a coffeemaker having a separate heater functioning to keep the coffee warm after it has been brewed. More specifically, the present invention relates to a control for the keep warm heater.
Conventional automatic drip-type coffeemakers have enjoyed widespread use and commercial acceptance. Drip coffeemakers are a very popular consumer small appliance. Such a coffeemaker typically includes a reservoir for containing water, a hot water generator to heat the water, a spreader for receiving the hot water and a container or basket ("brew basket") adapted to hold the coffee grind (generally in a filter) and to receive the heated water. The heated water is directed by the spreader onto the coffee grind contained in the brew basket. The brewed coffee is drained from the brew basket through an aperture located at the bottom thereof into a carafe supported on a base portion of the housing.
Many coffeemakers include heating means for maintaining the temperature of the coffee in the carafe at a relatively warm level after it has been brewed. Such means generally include utilization of the heater for the hot water generator.
One of the problems associated with using the hot water generator heater as the heating means to keep the brewed coffee warm is that the heater is capable of delivering many times the watts required for the keep warm function. For example, the rated wattage of the heater for the hot water generator may be in the range of 950 through 1000 watts whereas only about 50 to 75 watts may be required to obtain the necessary heat for the keep warm function. The use of the high wattage heater to perform the keep warm function results in increased operating costs for the user of the coffeemaker.
Some coffeemakers have used a separate heater rated at a lower wattage to perform the keep warm function. However, many higher quality recently introduced coffeemakers allow the user to select brewing cycles which will create lesser or greater amounts of coffee, for example, one to four cups or five through ten cups. In such instances, even the use of a second heater dedicated to the keep warm function is not totally satisfactory since the heat produced to satisfy the requirements for maintaining the desired temperature of ten cups of coffee will exceed the heat required to maintain the temperature of four cups of coffee.
Accordingly, it is an object of this invention to regulate the keep warm function heater so that the heat generated by the keep warm heater corresponds to the quantity of coffee to be heated or may be varied to satisfy the specific taste of an individual consumer.